**Core Concept**
The Gleason score is a grading system used to evaluate the prognosis of prostate cancer by assessing the aggressiveness of the tumor based on the glandular differentiation of the tumor cells. It is a crucial tool in determining the stage and treatment of prostate cancer.

**Why the Correct Answer is Right**
The Gleason score is calculated by adding the grades of the two most prevalent tumor patterns in the prostate biopsy. The grades range from 1 to 5, with 1 being the least aggressive and 5 being the most aggressive. The sum of the two grades gives a total score between 2 and 10, with higher scores indicating a more aggressive tumor. The Gleason score is an independent predictor of prostate cancer-specific mortality and is used to guide treatment decisions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the Gleason score. While the Gleason score is indeed used to predict the aggressiveness of prostate cancer, it is not a direct measure of cancer progression.

**Option B:** This option is incorrect because it is not a true statement about the Gleason score. The Gleason score is not a direct measure of cancer stage, but rather a predictor of cancer aggressiveness.

**Option C:** This option is incorrect because it is not a true statement about the Gleason score. The Gleason score is not a direct measure of cancer recurrence, but rather a predictor of cancer aggressiveness.

**Option D:** This option is incorrect because it is not a true statement about the Gleason score. The Gleason score is not a direct measure of cancer metastasis, but rather a predictor of cancer aggressiveness.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the Gleason score is a continuous variable, not a categorical one, and should be interpreted within the context of the entire clinical picture. A Gleason score of 7, for example, does not necessarily imply an intermediate-risk cancer, as the score is a combination of the two most prevalent tumor patterns.

**Correct Answer:** D.